Endress+Hauser TOCII CA72TOC, Руководство по эксплуатации

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TOCII CA72TOC Installation
Hauser 15
3.3.5 Preparing the chemicals
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Warning!
Accidents with chemicals can kill, blind, burn, or damage lungs. Many chemicals are poisonous or
corrosive; some are explosive, by themselves or in combination. Others are hazardous because they
can be absorbed easily through skin or the respiratory system. When working with any chemicals,
always observe the precautions in the section "Precautions regarding use of chemicals".
The analyzer requires the following chemical solutions:
• Stripper solution
Nitric acid HNO
3
(CAS: 7697-37-2) conc. 25 %
This acid is used to acidify the sample. In this way, the carbonate ion CO
3
is converted to CO
2
and the dissolved CO
2
is removed from the solution (TIC stripping).
• Parent solution
Potassium hydrogen phthalate (KHP (CAS: 877-24-7)) with a concentration of 5 000 mg TOC/l
This parent solution for calibrating and adjusting the analyzer is used as a diluted standard in the
measuring range from 0 to 600 mg TOC/l. In the event of high KHP concentrations and sample
acidification (pH < 2.5), there is the risk of KHP precipitating in the solution.
• Parent solution
Citric acid (CAS: 5949-29-1) with a concentration of 100 000 mg TOC/l
This parent solution for calibrating and adjusting the analyzer is used as a diluted standard in the
measuring range from 600 mg TOC/l onwards.
The stripper solution and the parent solutions are available from Hauser (see "Accessories"
chapter).
Specifying the standard concentrations
The right choice of standard concentration is key to the accuracy of the measurement method.
Before you specify the concentrations of the standard solutions, determine what concentration
range the device should measure. The most common concentrations should be covered by the
standard solutions.
Please note, however, that there should be a concentration ratio of between 1:4 and 1:20 between
the two standard solutions.
If a limit value is to be monitored, it makes sense for the concentration of the standard to correspond
to the concentration of a limit value as this guarantees maximum precision when monitoring.
!
Note!
Please note that no measurement method can provide accurate measurement results over a span
greater than 1:30.
Example:
20 and 200 mg/l should be selected here as the standard solutions. The system can then measure
accurately in the range from 10 to 300 mg/l (taking the measuring range of the system into
account). A higher measured value deviation can be expected below a concentration level of
10 mg/l and above a concentration level of 300 mg/l.
Concentration to be measured: 3 to 300 mg/l
Most frequent concentration: 50 to 150 mg/l
Limit value to be monitored: 200 mg/l